KR20190112598A - Detecting Size of Print Medium Using Sensors Available Along Paper Path - Google Patents

Abstract

The disclosed image forming apparatus is located in a paper feeder, a load detection sensor for detecting whether the print medium is loaded, an excess load detection sensor for detecting an excess load capacity of a discharge unit, a detection signal for a load detection sensor and an excess load detection sensor. And a control unit for detecting the size of the print medium by the combination of the control units and controlling the image forming unit to perform printing by applying different print modes according to the size of the detected print medium.

Description

Detecting Size of Print Medium Using Sensors Available Along Paper Path}

The electrophotographic image forming apparatus supplies toner to an electrostatic latent image formed on the photosensitive member to form a visible toner image on the photosensitive member, transfers the toner image onto a print medium, and then fixes the transferred toner image on a print medium to print. Print an image on the medium.

The fixing unit may have a heating member and a pressing member engaged with each other to form the fixing nip. The print medium is subjected to heat and pressure as it passes through the fixing nip. As a result, the toner image is fixed to the print medium. The width of the heating element corresponds to the width of the print medium of the maximum size available. In the printing process, the entire width of the heating member is heated.

When a narrow width of the print medium passes through the fixing nip, since the heat of the heating member is not transferred to the print medium in the area where the print medium does not pass, the temperature may be higher than that in which the print medium passes. In the continuous printing of the narrow print media, the temperature of the region through which the print media passes may be higher than that of the region through which the print media passes.

1 is a schematic structural diagram of an embodiment of an electrophotographic image forming apparatus.
2 is a schematic plan view of a paper feeding unit.
3 is a diagram illustrating an embodiment of a sensor.
4 is a plan view illustrating an arrangement position of first and second sensors.
5 is an example of a control block diagram.

1 is a schematic structural diagram of an embodiment of an electrophotographic image forming apparatus. Referring to FIG. 1, a paper feeding unit 100 on which a printing medium P is loaded, and a discharge unit 300 on which a printing medium P on which printing is completed are loaded is illustrated. The printing path 400 connects the paper feeder 100 and the discharge unit 300. The image forming unit 200 is disposed in the printing path 400.

The print media P loaded on the paper feeder 100 is drawn out one by one and transported along the printing path 400. In the present embodiment, the paper feeding unit 100 is shown in the form of a paper cassette, but the example of the paper feeding unit 100 is not limited thereto. The paper feeder 100 may be, for example, in the form of a multipurpose feeder tray.

2 is a schematic plan view of the paper feeding unit 100. Referring to FIG. 2, the print medium P may be loaded on the paper feeder 100 in a center aligned manner. The paper feeder 100 may include a pair of guide members 101 and 102. The pair of guide members 101 and 102 guide both ends in the width direction of the print medium P such that the print medium P is loaded in the paper feeding part 100 in a center aligned manner. In order to adjust the spacing between the pair of guide members 101 and 102 in response to the width of the print medium P, the pair of guide members 101 and 102 are accessible / spaced from each other. The pair of guide members 101 and 102 may have a structure that is synchronized and accessible / spaced from each other. In order to load the wide print medium P1, a pair of guide members 101 and 102 may be positioned as shown in solid lines in FIG. 2, and in order to load the narrow print medium P2. The pair of guide members 101, 102 may be positioned as shown in dashed lines in FIG. 2.

The image forming unit 200 prints an image by an electrophotographic method on the print medium P transported along the printing path 400. The image forming unit 200 may include a developing unit 210, an exposure machine 220, a transfer roller 230, and a fixing unit 240. The developing unit 210 supplies the toner contained therein to the electrostatic latent image formed on the photosensitive drum 21 to develop the electrostatic latent image into a visible toner image.

The photosensitive drum 21 may be an example of a photosensitive member having an electrostatic latent image formed on a surface thereof, and may include a conductive metal pipe and a photosensitive layer formed on an outer circumference thereof. The charging roller 22 charges the surface of the photosensitive drum 21 to a uniform electric potential.

The exposure machine 220 irradiates the photosensitive drum 21 with light modulated in correspondence with the image information to form an electrostatic latent image on the photosensitive drum 21. As the exposure machine 220, a laser scanning unit (LSU) using a laser diode as a light source, an LED exposure machine using a light emitting diode (LED) as a light source, and the like may be employed.

The developing roller 23 is for supplying a developer, for example, a toner, contained in the developing unit 210 to the photosensitive drum 21 to develop an electrostatic latent image into a visible toner image. The developing bias voltage may be applied to the developing roller 23. When the one-component developing method is adopted, the toner may be accommodated in the developing unit 210. When the two-component developing method is employed, the developing unit 210 may accommodate toner or toner and a carrier. Although not shown in the drawings, the developing unit 210 is a supply roller for supplying the developer contained in the developing unit 210 to the developing roller 23, and is attached to the surface of the developing roller 23 so that the photosensitive drum 21 and the developing roller ( The control member 23 may further include a regulating member for regulating the amount of the developer supplied to the developing area facing the 23), a stirring member for stirring the developer contained in the developing unit 210, and the like.

The transfer roller 230 is an example of a transfer machine for transferring the toner image from the photosensitive drum 21 to the print medium P. FIG. The transfer roller voltage is applied to the transfer roller 230 for transferring the toner image onto the print medium P. Instead of the transfer roller 230, a corona transfer machine or a pin scorotron type transfer machine may be employed.

The printing medium P is picked up one by one from the sheet feeding unit 100 by the pickup roller 11, and is transferred to the area where the photosensitive drum 21 and the transfer roller 230 face each other by the transfer rollers 12 and 13. do.

The fixing unit 240 applies heat and pressure to the toner image transferred to the printing medium P to fix it to the printing medium P. The print medium P having passed through the fixing unit 240 is discharged and loaded into the discharge unit 300 by the discharge roller 19.

The cleaning blade 24 is an example of cleaning means for removing toner and foreign matter remaining on the surface of the photosensitive drum 21 after the transfer process. Instead of the cleaning blades 24, other types of cleaning devices, such as brushes, may be employed.

With the above configuration, the exposure apparatus 220 scans the photosensitive drum 21 with light modulated in parallel with the image information to form an electrostatic latent image. The developing roller 23 supplies toner to the electrostatic latent image to form a visible toner image on the surface of the photosensitive drum 21. The print medium P loaded on the paper feeder 100 is transferred to the area where the photosensitive drum 21 and the transfer roller 230 face by the pickup roller 11 and the transfer roller 12, 13, and toner image. Is transferred from the photosensitive drum 21 onto the printing medium P by the transfer bias voltage applied to the transfer roller 230. When the print medium P passes through the fixing unit 240, the toner image is fixed to the print medium P by heat and pressure. The print medium P, which has been fixed, is discharged by the discharge roller 19 and loaded on the discharge unit 300.

The fixing unit 240 may include a heating member 241 and a pressing member 242 which mesh with each other to form a fixing nip through which the print medium P passes. The heating member 241 may be heated by the heat source 243. The heating member 241 may be, for example, in the form of a metal roller, an endless belt, or the like. The heat source 243 may be, for example, a halogen lamp, ceramic heater, or the like. The width of the heating member 241 may correspond to the width of the print medium (P). While the print medium P passes through the fixing nip, the heat of the heating member 241 is transferred to the print medium P and the toner image. The whole width of the heating member 241 is heated while printing is performed. When the narrow print medium P2 passes through the fixing nip, the surface of the heating member 241 is divided into a non-contact area not in contact with the contact area in contact with the print medium P2 in the width direction. Since the heat of the heating member 241 is not transferred to the print medium P2 in the non-contact area, the temperature may be higher than that of the contact area. When a plurality of sheets are continuously printed using the narrow print medium P2, the temperature of the non-contact area may be higher than that of the contact area. The increase in temperature of the heating member 241 may negatively affect the life of the fixing unit 240. In addition, heat may be transferred to other members inside the image forming apparatus, which may negatively affect the overall life of the image forming apparatus.

In view of the above, the control unit 500 may print the image in a different printing mode, for example, one selected from the first mode and the second mode, depending on the width of the print medium P. 200) can be controlled. The controller 500 may stop printing and output a print error signal according to the feeding state of the print medium P. FIG. The first mode is a normal print mode, and is applied to the print medium P1 having the maximum size that can be loaded in the paper feeder 100. The second mode is a low speed printing mode, and is applied to a print medium P2 whose width is narrower than that of the print medium P1. For example, the print medium P1 may be A4 or LTR paper, and the print medium P2 may be A5 or B5 paper. When the narrow print medium P2 is used, the printing speed is reduced, thereby securing the cooling time of the non-contact area, thereby reducing the risk of overheating of the non-contact area.

As an example, the controller 500 controls the image forming unit 200 to print an image at a first process speed in the first mode, and displays the image at a second process speed lower than the first process speed in the second mode. The image forming unit 200 may be controlled to print. Here, the process speed is a speed at which the image forming unit 200 forms an image, and means a linear speed of the photosensitive drum 21 or a transport speed of the print medium P. FIG.

For example, the controller 500 may set the interval between the preceding print and the next print as the first interval in the first mode and the second interval greater than the first interval in the second mode during continuous printing. In this case, the first process speed and the second process speed may be the same, and the second process speed may be smaller than the first process speed.

In order to distinguish between the first mode and the second mode, it is necessary to detect the width of the print medium P. The controller 500 detects the width of the print medium P by a combination of detection signals of two sensors (first sensor and second sensor) that detect the print medium P in the image forming process, and detects the detected print. The image forming unit 200 is controlled to perform printing in one of the first mode and the second mode in which the printing speed is slower than the first mode according to the width of the medium P. FIG. The controller 500 detects a feeding state of the print medium P by a combination of detection signals of two sensors (first sensor and second sensor) that detect the print medium P in the image forming process, and detects According to the feeding state of the print medium P, printing can be stopped and a print error signal can be output.

3 is a diagram illustrating an embodiment of a sensor. Referring to FIG. 3, the sensor may include an actuator 551 that contacts and rotates the print medium P, and a sensing unit 552 that is turned on / off by the actuator 551. The sensing unit 552 may be, for example, a photo interrupter including a light emitting unit and a light receiving unit. For example, when the print medium P is not detected, the actuator 551 is located at the position shown by the solid line in FIG. 3, and light emitted from the light emitting unit is received by the light receiving unit, and the sensing unit 552 is turned off. (OFF) state is turned on. When the print medium P pushes the actuator 551 and rotates it to the position shown by the dotted line in FIG. 3, the actuator 551 is positioned between the light emitting portion and the light receiving portion, and light emitted from the light emitting portion is directed to the actuator 551. The light is blocked by the light receiving unit, and the sensing unit 552 is turned on. The sensing unit 552 may be connected to the control unit 500 by electrical means (not shown). Hereinafter, when the print medium P is detected by the sensor, the detection signal of the sensor is called an "on state", and when the print medium P is not detected, the detection signal of the sensor is called an "off state".

4 is a plan view illustrating an arrangement position of first and second sensors. Referring to FIG. 4, a first printing medium P1 to which a first mode is applied and a second printing medium P2 to which a second mode is applied are shown. The second print medium P2 is narrower in width than the first print medium P1. The second print medium P2 is a print medium having a maximum width to which the second mode is applied.

The centered first print medium P1 has one end P1-1 and the other end P1-2 in the width direction. The centrally aligned second printing medium P2C includes one end P2C-1 and the other end P2C-2 in the width direction. The first sensor 561 is an area S1 between the one end P1-1 of the centrally aligned first print medium P1 and the one end P2C-1 of the second print medium P2C centrally aligned. Is arranged to detect the print medium (P). For example, the actuator 551 of the first sensor 561 may be located in the area S1. When the pair of guide members 101 and 102 are properly adjusted as shown in FIG. 2, the sheet feeding unit 100 is arranged in a centered manner as indicated by reference numeral P2C in FIG. 4. Can be loaded on. In this case, the first print medium P1 and the second print medium P2 may be distinguished and detected only by the first sensor 561. For example, the control unit 500 may recognize that the first print medium P1 is detected when the detection signal in the on state is input from the first sensor 561. The controller 500 recognizes that the second print medium P2 is detected when the detection signal in the on state is not input from the first sensor 561, that is, when only the detection signal in the off state is input from the first sensor 561. can do. When the print medium P is in the normal feeding state, the control unit 500 detects the width of the print medium P and the feeding state of the print medium P according to the detection signal input from the first sensor 561. can do.

The print medium P may be abnormally fed. For example, the second print medium P2 may be loaded on the paper feeder 100 while the pair of guide members 101 and 102 are positioned at the positions shown by the solid lines in FIG. 2. Then, the second print medium P is laterally aligned with one end P1-1 of the first print medium P1 as indicated by P2R in FIG. 4 or as indicated by P2L in FIG. 4. It may be side-aligned with the other end P1-2 of P1). When the second print medium P2 is side-aligned with the other end P1-2 of the first print medium P1 as indicated by P2L, the first sensor 561 is turned off. The first printing medium P1 and the second printing medium P2 may be distinguished and detected based on the detection signal of the first sensor 561. However, when the second print medium P is side-aligned with one end P1-1 of the first print medium P1 as indicated by P2R, the detection signal of the state from the first sensor 561 is input. Therefore, the controller 500 may not detect the first print medium P1 and the second print medium P2 based on the detection signal of the first sensor 561.

In this embodiment, the second sensor 562 is additionally employed. The second sensor 562 is arranged at the other end P2R− of the second printing medium P2 (indicated by P2R in FIG. 4) which is laterally aligned toward one end P1-1 of the centrally aligned first printing medium P1. 2) and the print medium P in the area S2 between the other end P2C-2 of the second print medium P2 (indicated by P2C in FIG. 4) that is centered. For example, the actuator 551 of the second sensor 562 may be located in the area S2. Since the second sensor 562 is arranged to detect the print medium P in the area S2, a plurality of sensors which will be described later, which detect the print medium P in the image forming process, perform their original functions and simultaneously perform the second function. It may be utilized as the sensor 562.

The control unit 500 feeds the first print medium P1 and the second print medium P2 into a normal feeding state by a center alignment method by a combination of detection signals of the first sensor 561 and the second sensor 562. The first print medium P1 and the second print medium P2 may be distinguished and detected even when the second print medium P2 is incorrectly loaded in the side alignment method as well as the case where it is loaded on the 100. The controller 500 may control the image forming unit 200 by applying one of the first mode and the second mode according to the detection result of the width of the print medium P. FIG. The control unit 500 may stop printing and output a print error signal according to the detection result of the feeding state of the print medium P. FIG. Table 1 shows the relationship between the type of the printing medium P, the combination of the detection signals of the first sensor 561 and the second sensor 562, and the print mode.

Print Media / Feed Status First sensor Second sensor Print mode First print medium (P1) On On First mode Second Print Media (P2) / P2C off On 2nd mode Second Print Media (P2) / P2R On off Print error Second Print Media (P2) / P2L off On 2nd mode

The controller 500 may control the image forming unit 200 to perform printing in the first mode when a detection signal in a state of being turned on from both the first sensor 561 and the second sensor 562 is input. When the detection signal in the off state is input from the first sensor 561 (that is, when the detection signal in the on state is not input), the controller 500 may perform printing in the second mode. ) Can be controlled. The control unit 500 detects an on-state detection signal from the first sensor 561 and an off-state detection signal from the second sensor 562 (that is, detection of the on-state state from the second sensor 562). If a signal is not input), it may be recognized as a feeding error state and a print error signal may be output. As a result, the user may be induced to check the loading state of the print medium P, the transport state of the print medium P, and the like, and thus, unnecessary printing and the overheating of the fixing unit 240 may be prevented.

5 is an example of a control block diagram. Referring to FIG. 5, the controller 500 may include a central processing unit (CPU) 501 and a memory 502. The memory 501 may store first and second control factors corresponding to the first and second modes, respectively. The control unit 500 selects any one of the first and second modes from the combination of the detection signals of the first and second sensors 561 and 562, and selects one of the first and second control factors from the memory 502. The image forming unit 200 may be controlled by reading a corresponding control factor. For example, when controlling the processor speed according to the printing mode, the control factor may be a driving speed of the driving motor 201 driving the rotating members of the image forming unit 200. For example, in the case of controlling the interval between printings in accordance with the printing mode, the control factor may be, for example, the operating interval of the clutch 202 which controls the driving of the pickup roller 11.

The image forming apparatus may include a plurality of sensors that detect the print medium P transported along the print path 400. In this embodiment, a separate sensor for detecting the width of the print medium P is not employed. The control unit 500 detects the width of the print medium P according to a combination of detection signals of two sensors among a plurality of sensors, and compares the first mode and the first mode according to the detected width of the print medium P. The image forming unit 200 is controlled to perform printing in one of the second modes having a slow printing speed. In addition, the control unit 500 detects the feeding state of the printing medium P by the combination of detection signals of two sensors among the plurality of sensors, stops printing according to the feeding state of the detected printing medium P, and prints. Error signal can be output. According to such a configuration, a separate sensor for detecting the width and the feeding state of the print medium P, and electrical wiring for transmitting the signal of the sensor to the control unit 500 can be omitted, thereby reducing the part cost. It is also advantageous to implement a compact image forming apparatus.

For example, the plurality of sensors may include a paper empty sensor 510 for detecting whether the print medium P is loaded in the paper feeder 100, and a print medium P supplied to the image forming unit 200. Alignment sensor (520) that provides a reference position of the), is installed in the outlet jam sensor 530, the discharge unit 300 is installed at the outlet of the fixing unit 240 detects the jam in the fixing unit 240 It may include an excess load detection sensor 540 for detecting an excess load capacity of the discharge unit 300.

The sensors 510, 520, 530, 540 may have the structure shown in FIG. 3, for example. The paper empty sensor 510 is positioned at the position shown by the solid line of FIG. 3 when the print medium P is not loaded in the paper feeder 100, and the detection signal is kept in the off state. The alignment sensor 520 may be located at the inlet side of the feed roller 13. When the print medium P is detected by the alignment sensor 520, the controller 500 recognizes that the tip of the print medium P has passed through the alignment sensor 520. Thereby, the reference position of the print medium P can be provided. The controller 500 is configured such that the tip of the toner image formed on the photosensitive drum 21 is aligned with the transfer nip when the tip of the print medium P reaches the transfer nip in which the photosensitive drum 21 and the transfer roller 230 face each other. The exposure start time of the exposure apparatus 220 may be controlled to be reached. The discharge jam sensor 530 is turned on as shown by the dotted line in FIG. 3 when the print medium P passes. The control unit 500 may recognize that the jam is generated in the fixing unit 240 when the discharge jam sensor 530 is turned on and the discharge jam sensor 530 does not turn off even after a predetermined time has elapsed. The overload detection sensor 540 is in an on state shown by a dotted line in FIG. 3 by the print medium P discharged to the discharge unit 300, and is in an off state shown by a solid line in FIG. 3 after the discharge is completed. . When the excess stacking detection sensor 540 is kept in the on state without being returned to the off state, the controller 500 may recognize that the amount of the print medium P loaded in the discharge unit 300 exceeds the stacking capacity. .

The first sensor 561 may be an overload detection sensor 540. The overload detection sensor 540 is disposed to detect the print medium P discharged from the area S1 of FIG. 4 in the width direction.

The second sensor 562 may be selected from among the sensors for detecting the printing medium P, which are installed in the paper feeding unit 100 and the printing path 400 between the paper feeding unit 100 and the discharge unit 300. In FIG. 1, only the loading detection sensor 510, the alignment sensor 520, and the discharge jam sensor 530 are illustrated, but an additional sensor may be further disposed between the pickup roller 11 and the transfer roller 13. In the present embodiment, any one of the load detection sensor 510, the alignment sensor 520, and the discharge jam sensor 530 is employed as the second sensor 562. Any one of the loading detection sensor 510, the alignment sensor 520, the discharge jam sensor 530 is arranged to detect the print medium (P) in the area (S2) of Figure 4 in the width direction. The second sensor 562 is arranged to detect the print medium P in the area S2, such that a plurality of sensors, for example, a loading sensor 510, an alignment sensor 520, and a discharge jam sensor 530. May be utilized as the second sensor 562. By placing the loading detection sensor 510, the alignment sensor 520, the discharge jam sensor 530 in the area (S2), the inherent functions of these sensors can be performed, and at the same time the width of the print medium (P) A function as the second sensor 562 for detecting the paper feeding state may also be performed.

As shown in Table 1, the control unit 500 includes any one of the loading sensor 510, the alignment sensor 520, the discharge jam sensor 530, and the first sensor 561 as the second sensor 562. The image forming unit 200 may be controlled to print in any one of the first mode and the second mode according to the combination of the detection signals of the overload detection sensor 540 as a second mode. In addition, the control unit 500 may stop printing and output a print error signal according to the combination of the above-described detection signals. Accordingly, without employing a separate sensor for detecting the width of the print medium P, the control unit 500 controls the first print medium P1 and the second print medium P2C, P2L, and P2R shown in FIG. P2) can be distinguished from each other, and the image forming unit 200 can be controlled to print an image in a first mode for the first printing medium P1 and in a second mode for the second printing medium P2. Can be. In addition, when the second print medium P2 is fed in the P2R state, a print error signal may be output.

Substantially, the image is successfully printed only on the first printing medium P1 and the second printing medium P2 in the P2C state, and the image is not properly printed on the second printing medium P2 in the P2L and P2R states. That is, only a part of the image to be printed is printed on the second printing medium P2 in the P2L and P2R states. When the distance between the user and the image forming apparatus is far, for example, when the image forming apparatus is a network printer, the user cannot know the loading state of the print medium P in the paper feeding unit 100. However, the second mode can be applied not only to the second printing medium P2 in the P2C state properly loaded in the paper feeding unit 100 but also to the second printing medium P2 in the P2L and P2R states that are inappropriately loaded. Overheating of the fixing unit 240 may be effectively prevented in a plurality of continuous printings on the second printing medium P2. In addition, when the second print medium P2 is fed in the P2R state, by printing a print error signal, unnecessary printing and consequent overheating of the fixing unit 240 can be prevented.

If the detection signal of the loading detection sensor 510 is turned off in the image forming process, the print medium P is not loaded in the paper feeder 100 or all of the print medium P loaded in the paper feeder 100 is used. Or when the second printing medium P2 is loaded in the P2R state. In any of the above cases, since normal printing cannot be performed, the controller 500 may stop printing and output a print error signal. This may induce the user to check the loading state of the print medium (P). In addition, as described above, since the image is not properly printed on the second printing medium P2 in the P2R state, unnecessary printing may be prevented. The print error signal may be output through the output device (FIG. 5: 503). The output device 503 may be, for example, a buzzer, a display, an equalization, a host device of the user, or the like.

When the detection signal of the alignment sensor 520 does not change from the off state to the on state in the image forming process, a transfer failure occurs in the printing path 400 from the paper feeder 100 to the alignment sensor 520, or the second printing medium This is the case when (P2) is loaded in the P2R state. When the alignment sensor 520 is employed as the second sensor 562, if the detection signal of the alignment sensor 520 does not change from the off state to the on state, the control unit 500 causes the print medium P to be discharged from the discharge unit 300. It is possible to drive the image forming apparatus for a time sufficient to reach, and to check whether the detection signal in the on state from the overload detection sensor 540 is input during the driving time. When the detection signal in a state of being turned on from the overload detection sensor 540 is input, the second print medium P2 is loaded in the paper feeding unit 100 in a P2R state. Of course, since the image is not properly printed on the second print medium P2 in the P2R state, the controller 500 may stop printing and output a print error signal. If a detection signal in a state of being turned on from the overload detection sensor 540 is not input, since a transfer failure has occurred, the controller 500 may stop printing and output a print error signal. The print error signal may be output through the output device (FIG. 5: 503). The output device 503 may be, for example, a buzzer, a display, an equalization, a host device of the user, or the like.

If the detection signal of the discharge jam sensor 530 does not change from the off state to the on state during the image forming process, a transfer failure occurs in the printing path 400 from the paper feeding unit 100 to the fixing unit 240, or the second printing medium. This is the case when (P2) is loaded in the P2R state. When the discharge jam sensor 530 is employed as the second sensor 562, if the detection signal of the discharge jam sensor 530 does not change from the off state to the on state, the control unit 500 determines that the print medium P is discharged. It is possible to drive the image forming apparatus for a time sufficient to reach 300, and to check whether the detection signal in the on state from the overload detection sensor 540 is input during the driving time. When the detection signal in the on state from the overload detection sensor 540 is input, it corresponds to the case where the second printing medium P2 is loaded in the P2R state. Of course, since the image is not properly printed on the second print medium P2 in the P2R state, the controller 500 may stop printing and output a print error signal. If a detection signal in a state of being turned on from the overload detection sensor 540 is not input, since a transfer failure has occurred, the controller 500 may stop printing and generate a print error signal. The print error signal may be output through the output device (FIG. 5: 503). The output device 503 may be, for example, a buzzer, a display, an equalization, a host device of the user, or the like.

Although the present disclosure has been described with reference to the embodiments illustrated in the drawings, this is merely exemplary, and various modifications and equivalent other embodiments may be made by those skilled in the art. I will understand. Therefore, the true technical protection scope of the present disclosure will be defined by the claims below.

Claims (15)

A center-aligned paper feeder on which a print medium is loaded;
An image forming unit for printing an image by an electrophotographic method on a printing medium supplied from the paper feeding unit;
A discharge unit for discharging and stacking a print medium on which an image is printed;
A load detection sensor positioned in the paper feeder and detecting whether the print medium is loaded;
An excess load detection sensor for detecting an excess load capacity of the discharge unit;
The image forming unit is configured to detect the size of the print medium by a combination of the detection signals of the load detection sensor and the excess load detection sensor, and to perform printing by applying different print modes according to the size of the detected print medium. And a control unit. The method of claim 1,
The print mode includes a first mode and a second mode in which a printing speed is lower than that of the first mode. The method of claim 2,
The print medium includes a first print medium to which the first mode is applied, and a second print medium having a width smaller than that of the first print medium and to which the second mode is applied.
The overload detection sensor detects a print medium between one end of the centered first print medium and one end of the second centered print medium,
And the loading detection sensor detects a print medium between the other end of the second print medium which is laterally aligned toward the one end of the first print medium and the other end of the second print medium which is centrally aligned. The method of claim 3, wherein
The control unit detects a paper feed state of the print medium by a combination of the detection signals of the load detection sensor and the excess stack detection sensor, stops printing according to the fed state of the detected print medium, and outputs a print error signal. An image forming apparatus. The method of claim 4, wherein
And the control unit controls the image forming unit to perform printing in the first mode when a detection signal in a state from both the excess stacking detection sensor and the stacking detection sensor is input. The method of claim 4, wherein
And the control unit controls the image forming unit to perform printing in the second mode when an off state detection signal is input from the excess stacking detection sensor. The method of claim 4, wherein
And the control unit stops printing and outputs a print error signal when an off state detection signal is input from the loading status detection sensor. The method according to any one of claims 1 to 7,
The control unit controls the image forming unit to print an image at a first process speed in the first mode, and the image forming unit to print an image at a second process speed lower than the first process speed in the second mode. Image forming apparatus for controlling. The method according to any one of claims 1 to 7,
And the control unit sets the interval between printings during the continuous printing to a first interval in the first mode and to a second interval larger than the first interval in the second mode. A paper feeder on which a print medium is loaded;
An image forming unit for printing an image on a printing medium by an electrophotographic method;
A discharge unit on which a print medium on which an image is printed is loaded;
A plurality of sensors positioned on a printing path from the paper feeder to the discharge unit to detect the print medium;
A width of the print medium is detected by a combination of detection signals of two sensors among the plurality of sensors, and a selected one of a first mode and a second mode slower than the first mode according to the detected width of the print medium And a controller which controls the image forming unit to perform printing in a mode of,
The print medium includes a first print medium to which the first mode is applied, and a second print medium having a width smaller than that of the first print medium and to which the second mode is applied.
The two sensors,
A first sensor detecting a print medium between one end of the centered first print medium and one end of the centered second print medium;
And a second sensor detecting a print medium between the other end of the second print medium which is laterally aligned toward the one end of the first print medium and the other end of the second print medium which is centrally aligned. . The method of claim 10,
And the control unit controls the image forming unit to perform printing in the first mode when a detection signal in a state of being turned on from both the first sensor and the second sensor is input. The method of claim 11,
And the control unit controls the image forming unit to perform printing in the second mode when a detection signal of an off state is input from the first sensor. The method according to any one of claims 10 to 12,
The first sensor is an excess load detection sensor for detecting an excess load capacity of the discharge unit,
The second sensor may be installed at the paper feeder to detect whether or not the print medium is loaded, an alignment sensor to provide a reference position of the print medium supplied to the image forming unit, and an outlet of the fixing unit. The image forming apparatus of any one of the media jam sensor for detecting the jam in the fixing unit. The method of claim 13,
The second sensor is the loading status detection sensor,
And a control unit stops printing and outputs a print error signal when an off state detection signal is input from the loading status detection sensor. The method of claim 13,
The second sensor is any one of the alignment sensor and the media jam sensor,
And the control unit outputs a print error signal through an output device when the detection signal in the off state is input from the second sensor and the detection signal in the on state from the first sensor is not input.

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